Galic acid

The standard of rutin, galic acid, Folin–Ciocalteu’s phenol reagent, HPLC grade methanol, 2,2-diphenyl-1-picrylhydrazyl and ethanol were obtained from Sigma Aldrich (St. Louis, MO, USA), stevioside and rebaudioside A were from TransMIT (Geiben, Germany), HPLC-grade acetonitrile and sodium acetate were from Sharlau Chemie S. A. (Sentmenat, Spain), HCl, sodium carbonate and acetic acid were from Carl Roth (Karlsruhe, Germany), hexamethylenetetramine and aluminium chloride were from Thermo Fisher Scientific (Lancashire, UK). All solutions were prepared with ultrapure 18.2 MΩ water from a Watek ultrapure water purification system (Watek Ltd., Ledeč nad Sázavou, Czech Republic).

Galic acid, quercetin, 2,2-diphenyl-1-picryl-hydrazyl (DPPH free radical), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonate) (ABTS), the ferric-reducing antioxidant power (FRAP), Folin Ciocâlteu reagents, and lipopolysaccharides from Escherichia coli O111:B4 were purchased from Sigma-Aldrich Chemicals GmbH (Germany). The Bradford reagent was from Merck KGaA (Darmstadt, Germany). ELISA tests for the evaluation of IL-6, IL-31, IL-33, TNF-α, and STAT3 were from R&D Systems Inc. (Minneapolis, MN, USA). The goat polyclonal IgG antibody for NFκB and pNFκB and the secondary antibody mouse anti-goat and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) were bought from Santa Cruz Biotechnology Inc. (Santa Cruz, CA, USA). All the chemicals used were of analytical grade.

The following standards were used to identify and quantify the phenolics: apigenin 7-glucoside, kaempferol-3-glucoside, procyanidin B1, quercetin-3-glucoside, ferulic acid, p-coumaric acid (Fluka Chemie GmbH, Buchs, Switzerland); (+) catechin (Roth, Karlsruhe, Germany); 4-O-caffeoylquinic acid, neochlorogenic acid (3-caffeoylquinic acid), myricetin-3-galactoside, quercetin-3-galactoside, quercetin-3-rhamnoside, juglone (5-hydroxy-1,4-naphthoquinone), 1,4-naphthoquinone, caffeic acid, galic acid, ellagic acid, naringenin, (−)epicatechin (Sigma–Aldrich Chemie GmbH, Steinheim, Germany); and myricetin-3-rhamnoside, quercetin-3-arabinofuranoside, quercetin-3-arabinopyranoside (Apin Chemicals, Abingdon, UK).
The water used for all sample preparation, solutions and analyses was bi-distilled and purified using a Milli-Q water purification system (Millipore, Bedford, MA, USA). The acetonitrile and formic acid for the mobile phases were HPLC-MS grade (Fluka Chemie GmbH, Buchs, Switzerland).

2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl (DPPH), 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox), methanol, water and galic acid was purchased from Sigma-Aldrich (St. Louis, MO, USA). Folin–Ciocalteu’s phenol reagent, sodium carbonate (Na₂CO₃) and sodium nitrate were purchased from Chempur (Piekary Slaskie, Poland). Ultrapure water (resistivity 18.2 MΩ cm), obtained from a Milli-Q purification system (Millipore, Bedford, MA, USA), was used for all analyses. Teff flour, sorghum groats, lecithin, olives and beeswax were purchased at local stores.